310 million people live in US. Surveys go up and down a little, from year to year, but most likely, approx. 1% of these are vegans. That's 3.1 million vegans.
http://www.ars.usda.gov/is/pr/2000/000802.htm:
Nearly two-fifths of the U.S. population may be flirting with marginal vitamin B12 status if the population of Framingham, Mass., is any indication.
A careful look at 3,000 men and women in the ongoing Framingham Offspring Study found 39 percent with plasma B12 levels in the “low normal” range--below 258 picomoles per liter.
While this is well above the currently accepted deficiency level of 148 pmol/L, some people exhibit neurological symptoms in the higher range, said study leader Katherine Tucker. She is a nutritional epidemiologist at the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University in Boston.
Nearly 9 percent of the study population fell below the current deficiency level. And more than 16 percent fell below 185 pmol/L. “Many people may be deficient at this level,” said Tucker. “There is a question as to what the clinical cutoff for deficiency should be.
“I think there is a lot of undetected vitamin B12 deficiency out there,” she said, noting that the study covered people from 26 to 83 years old. The research was funded by the Agricultural Research Service (ARS), USDA’s chief scientific agency.
This report has been quoted on wikipedia.org, with this text: "...there are reasons to believe that B12 deficiency is present in a far greater proportion of the population than 39% as reported by Tufts University". But that study didn't claim that 39% were deficient, but that 39% were in the low, normal range. "Nearly 9% were defined as deficient". Then there's of course the question about when someone should be defined as B12 deficient. At levels below 258 pmol? Below 148 pmol? Below 185 pmol?
Let's, for simplicity, say that not 39%, but only 13% of the population can be defined as B12 deficient (13% is just between the 9% and 16% values referred to above). Let's forget, for now, that the B12 levels in blood alone may not show the correct/relevant level we're looking for, due to a number of reasons (MMA/homocysteine not taken into consideration, low B-12 levels during pregnancy do not necessarily reflect a true tissue deficiency etc). If MMA/Hcy tests would have been taken as well, we may have seen that almost 80% of the population could be defined as having low B12 levels - whatever they eat. That's something to ponder on...
So - simplified version: 3.1 million vegans in USA. 13% of these are B12 deficient, again, if the same ratio should be applied on them as the Tuft results provided for the average population. That's 403,000 B12 deficient vegans in US alone! If we should use the 'low, normal range' as a reference (39%), which still ignores homocysteine and MMA values, the number would of course be three times as high, and that's even before we take MMA/homocysteine levels into consideration.
Since numbers change from year to year, let's try another example: let's say there are only 1 million vegans in USA, and that only 8%, and not 13% of the average population are B12 deficient. This would mean "only" 80,000 B12 deficient US vegans.
What if only 0.2% of the US population was vegan, and only as little 3.5% of these would have been B12 deficient? That's still more than 20,000 B12 deficient vegans in USA alone.
So - what's the point of all this?
It is:
1) If you hear about a B12 deficient vegan, don't be surprised. There are thousands of them, and remember - the numbers above are based on the B12 deficiency rate in the general population, not on vegans. For reasons discussed in other threads: while non-vegans may be deficient in more nutrients than we are, vegans usually have lower B12 levels than non-vegans.
2) If you're in doubt or have reasons to believe that you belong to the group of vegans that are deficient, do something about it.
If you are a child or have kids, remember that while recommendations for children are lower than for adults*, B12 is extra important when you grow up.
Current US RDA (Recommended Dietary Allowances, or "average daily level of intake sufficient to meet the nutrient requirements of nearly all (97%–98%) healthy individuals"):
- 0-6 months: 0.4 mcg
- 7-12 months: 0.5 mcg
- 1-3 years: 0.9 mcg
- 4-8 years; 1.2 mcg
- 9-13 years: 1.8 mcg
- 14+ years: 2.4 mcg
- Pregnant women: 2.6 mcg
- During lactation: 2.8 mcg.
For the records, I think all companies which manufacture/sell B12 supplements (outside Manchester, UK) are focusing on the validity of these numbers. We don't want our children to have too little or too much B12.
So you think that eating animal products may be the solution?
http://www.ars.usda.gov/is/pr/2000/000802.htm
Unlike what your favorite vegan organization/site may suggest, there's massive evidence and agreement that how much B12 we consume only is a part of the big B12 puzzle. It does not help if you eat enough B12 if you have a high consumption of B12 'killers'.Oddly, the researchers found no association between plasma B12 levels and meat, poultry, and fish intake, even though these foods supply the bulk of B12 in the diet. “It’s not because people aren’t eating enough meat,” Tucker said. “The vitamin isn’t getting absorbed.”
Since we cannot avoid all the stuff that kills or reduces B12 levels, one should expect to become B12 deficient on a 'natural' diet in an unnatural world. That's because the otherwise natural diet has been denaturalized by fertilizers, pesticides and much more - and because even if the food would have been in a 100% untouched state, all the other things we are exposed to (including some B12 'enemies' appearing in nature) affects how we absorb B12. Some of them may even reduce the B12 levels in the food we have eaten - after we have eaten it.
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